Service contents and terminals have been developed amazingly since the introduction of portable terminals. The services that supported only voice communications in the past have developed to Internet and broadcasting services including services, such as transmission of short text messages and photos, camera functions and Moving Picture Experts Group phase 1 or phase 2 (MPEG-1 or MPEG-2) audio layer-3 (MP3) functions have been added to the simple voice communication functions, and the screens of the terminals also have developed from black and white screens to high-quality liquid crystal display (LCD) screens. The communication services also have become multifunctional so that more than six services are currently used as compared with two or three services of the past in one band. Currently, display devices having touch functions on almost the entire front surface of the terminal have been implemented by bar type terminals. As the size of the display devices gradually gets larger, current consumption is also gradually increasing, and the terminal manufacturers are competing to reduce power consumption. As a measure for reducing current consumption, the brightness of a display device or a keypad assembly is automatically adjusted according to an illumination intensity of an external environment, by installing an illumination intensity sensor around a front panel. That is, the display screen becomes brighter in a bright environment, and becomes darker in a dark place so that a power source may be efficiently used.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.